A smart card may refer to a device that includes an embedded integrated circuit chip and internal memory. That internal memory may be located on the integrated circuit chip, or be a separate chip embedded within the card. A smart card may be a contact card; a contactless card, or may be capable of operating as a contact and a contactless card. Smart cards exist in a wide variety of form factors, including plastic cards, key fobs, watches, wearables, electronic passports and USB-based tokens and subscriber identification modules (SIMs) used in mobile phones.
A contact card communicates with a terminal (e.g., a card reader) by physically connecting to the terminal. For example, a contact card may comprise one or more contact pads that provide electrical connectivity to a terminal when the card and terminal are brought into suitable physical contact (e.g. by inserting the card into a slot within the terminal).
A contactless card communicates with a terminal without direct physical contact. Typically, a contactless card communicates with a terminal via radio waves. The contactless card may include an antenna to receive an electromagnetic signal, such as an RF signal, emitted from a terminal. Likewise, data from the card can be communicated back to the terminal by means of the card's antenna.
Some contactless cards are ‘passive’. A passive card powers the embedded chip from energy harvested from the signal emitted by the terminal. One way to harvest energy from the emitted signal is to arrange the antenna as a coil that induces a voltage across its terminals by means of induction when receiving the emitted signal.
Smart card technology is being implemented within a variety of devices used to perform increasingly varied functions, for example to perform payments, grant a user physical access to a region of an environment, to store personal identification information of the user; identify or authenticate a user etc. In some cases, it may be desirable for a device to be capable of performing multiple different functions.
There are several difficulties faced when trying to implement multiple functionalities into a device using smart card technology, particularly when a device designed to perform a ‘base’ or primary function is adapted to perform additional functions. One problem is that industry standards governing smart card technology were originally designed for payment/authentication cards. Existing infrastructure has therefore been designed in compliance with these standards that is suitable for powering this primary function of facilitating payments or transactions, which may place constraints on the power that can be consumed by any additional functionality placed onto the card. This problem may be compounded by the fact the additional functions may consume more power and/or require power for a longer period of time than the primary function of the card. A further problem is that for cards operating in a contactless mode, the power drawn by the additional functionality may affect the load modulation of the signal emitted by the terminal, which may appear as extra noise to the terminal.